This invention relates generally to mail sorting equipment and deals more particularly with an improved storage arrangement for receiving and stacking sorted envelopes in the storage section of a high speed mail sorting machine.
Modern automatic mail sorting machines have recently enjoyed considerable popularity, due largely to their ability to quickly sort the increasingly large volume of mail that must be handled on a daily basis by the postal service, governmental units, large businesses and other institutions. As described in my earlier U.S. Pat. No. 4,275,875, a high speed mail sorting machine typically includes an input section which receives a batch of envelopes to be sorted. The individual envelopes are separated from the stack and delivered one at a time on edge past a code reading device which reads a zip code or bar code printed on the envelope. The envelopes are then conveyed to a storage section of the machine and directed into sorting bins under the control of electronic circuitry which operates to route each envelope into a bin determined by the particular code detected by the code reader.
In this fashion, envelopes having the same code are directed into the same bin or bins. Often, outgoing mail is sorted according to zip code so that envelopes having a common destination are collected in the same bin or bins. Also, incoming mail can be routed to the proper department within a multiple department business or institution by properly sorting the incoming envelopes according to codes representative of the various departments.
In the past, mail sorting machines have been equipped with a large number of sorting bins which may be arranged along opposite sides of the envelope track through which the envelopes are conveyed in the bin section of the machine. As shown in my aforementioned U.S. Pat. No. 4,275,875, each bin typically has opposite side walls and a spring loaded back plate which travels back and forth along a shaft as envelopes are deposited in or removed from the bin. The back plate functions to hold the envelopes upright on their edges in cooperation with the side wall of the bin.
Although this type of arrangement has functioned in a satisfactory manner for the most part, it is relatively expensive because of the special components that are required. It is necessary for the back plate to move back and forth freely in order to avoid presenting undue resistance to the incoming envelopes and possibly jamming the machine. To provide the requisite freedom of movement, each back plate must have a low friction bearing, and each shaft must be specially machined and hardened. Both of these special items add significantly to the overall cost of the mail sorting machine. The contribution that these special components make to the expense can be readily appreciated when it is recognized that each bin requires one special shaft and two special bearings. In a machine having a large number of bins, the added cost takes on particular significance.
In addition to the expense, the sliding back plate arrangement requires in each bin a pair of upstanding side walls, a back wall, a shaft extending the entire length of the bin, and a spring loaded back plate extending across the bin. All of these parts can obstruct access to the sorting bins for removal of the mail and can significantly increase the time that is involved in removing mail from the bins. A related problem is that the bins occupy the entirety of the available surface area in the bin section of the machine, and there is no vacant and unobstructed space available to temporarily placing a mail tray or other object.
The present invention is aimed at eliminating these problems and has, as its principal goal, the provision of a more economical storage arrangement for receiving and stacking the sorted envelopes in a mail sorting machine. In addition to its economy, the storage arrangement of the present invention eliminates most of the components that obstruct access to the envelopes in conventional sorting bins. Moreover, the compact configuration of the stacking device provides ample table surface availability for the receipt of mail trays and the like.
In accordance with the invention, each storage area is equipped with a swing plate which is mounted to swing on an upright post. Each swing plate is located in the path of the incoming envelopes. As the envelopes enter the storage area, their front edges encounter the front face of the swing plate and progressively pivot it about the post as additional envelopes are deposited in the storage area. The swing plate is arranged at an acute angle relative to the envelopes and thus serves both as a back plate and as a side plate which is capable, by itself, of supporting the sorted envelopes in a progressively increasing stack.
Each swing plate has a sleeve which is fitted on the post and which has an inclined ramp on its lower edge. As the swing plate is progressively pivoted open by the incoming envelopes, the ramp rides along a roll pin that projects from the post. This raises the swing plate and causes it to be continuously urged toward the envelopes under the influence of gravity. The ramp and roll pin arrangement thereby assures that each swing plate is maintained against the leading edges of the envelopes which are stacked against it.
The swing plate arrangement of the present invention eliminates the need for bin side walls and back walls and for the spring loaded back plate and associated components that have previously been used in the bins of mail sorting machines. Consequently, the present invention is not only significantly improved in its economy, but it also eliminates the structure which in the past has obstructed access to the stacked mail and occupied all of the useful surface area in the storage section of the machine. At the same time, the storage arrangement of the present invention provides virtually the same storage capacity as the more expensive storage system that has been prevalent heretofore.